package com.leigq.basaltools.util;

import org.springframework.util.StringUtils;

import javax.servlet.http.HttpServletRequest;

/**
 * IP 工具
 * <br/>
 *
 * @author ：leigq
 */
public class IpUtils {

    private static final String UN_KNOWN = "unknown";

    /**
     * 获取用户真实IP地址，不使用request.getRemoteAddr()的原因是有可能用户使用了代理软件方式避免真实IP地址,
     * 可是，如果通过了多级反向代理的话，X-Forwarded-For的值并不止一个，而是一串IP值
     * <br/>
     * 参考：https://www.cnblogs.com/xiaoxing/p/6565573.html
     *
     * @param request the request
     * @return ip
     */
    public static String realIp(HttpServletRequest request) {
        String ip = request.getHeader("x-forwarded-for");
        if (!StringUtils.hasText(ip)) {
            return null;
        }
        if (UN_KNOWN.equalsIgnoreCase(ip)) {
            return null;
        }
        // 多次反向代理后会有多个ip值，第一个ip才是真实ip
        if (ip.contains(",")) {
            ip = ip.split(",")[0];
        }

        if (isUnKnown(ip)) {
            ip = request.getHeader("Proxy-Client-IP");
        }
        if (isUnKnown(ip)) {
            ip = request.getHeader("WL-Proxy-Client-IP");
        }
        if (isUnKnown(ip)) {
            ip = request.getHeader("HTTP_CLIENT_IP");
        }
        if (isUnKnown(ip)) {
            ip = request.getHeader("HTTP_X_FORWARDED_FOR");
        }
        if (isUnKnown(ip)) {
            ip = request.getHeader("X-Real-IP");
        }
        if (isUnKnown(ip)) {
            ip = request.getRemoteAddr();
        }
        return ip;
    }


    private static boolean isUnKnown(String ip) {
        return ip == null || ip.length() == 0 || UN_KNOWN.equalsIgnoreCase(ip);
    }
}
